"Mariah Carey didn't put her all into that song. I feel she was holding out on the KING" -- @shaznyc

"Very surprised that Mariah Carey didn't get arrested on the stage for that pitiful performance today." -- @ZedalzaNewYork

"Ok on a lighter note. Is it me or does it sound like Mariah Carey struggles when she sings. She sounded a mess. " -- @Keshia6

"As much respect and love I have for Mariah Carey and what she has done, her performance at Michael Jackson's memorial was a disgrace!!!" -- @jonasdesai

"So, CNN reported that Mariah Carey left during the memorial because she was too broken up ... I thought it was because her performance sucked" -- @Lilcinb

"I'm starting to think Mariah Carey was lip syncing all these years... how do you just loose your singing voice like that?" -- @keisean

And that's not even getting into those appalled by her low-cut neckline flashing her cleavage before noon.

Turns out, Mimi knew she wasn't up to snuff.

Tuesday evening, Carey took to
Twitter herself to explain over the course of two Tweets to her 921,157 followers that: "Trying to sing today was basically impossible for me. I could barely keep myself from crying. I'm sorry that/I wasn't able to pull it together and really do it right, but I was literally choked up when I saw him there in front of me."